Diazotypes on plastic surfaced carrier containing 5,5&#39; diresorcinol



Patented Feb. 20, 1951 DIAZOTYPES vON PLASTIC' SURFAGED .GABF-v RIERCONTAINING 5,5'JDIRESQRCINQL Fred W. Neumann, Nazareth, "ifPe-i assigngrto General Aniline & Film Corporation, New-York,

N. Y., a corporation of Delaware N Drawing. Application N ovemherlil,H49,

I Serial No. 126,696

1 C a ms- ,1

his i ti relates t dlezcty e liehtsehsi tive edi -a rt eu a l e the usef c ain mpon n s n th l ght i .iive layer-er coa i of a plastic e ri ceddiamant -ma eriel- T e a ti surf ce a u d ihihis ar plication isintended to include supports made entirely of plastic materials such ascellulose esters and others and regeneratedcellulose and supports ofnon-plastic materials such as paper which have been surfaced with acoating integral therewith of such a plastic material.

In the photo-reproduction of line or continuous tone originals by meansof the diazotype process, such as tracings or semi-transparentengineering drawings or typewritten documents by the diazotype positivereproduction method, it is highiy desirable that the image be reproducedin a shade which will give high contrast to the reproduced lines orother figures of the original. The photo-reproduction must also be fastto light and to water and possess good photographic density.Accordingly, the selection of dye components for the production of thelight-sensitive layer and the developer cannot be made merely on thebasis of obtaining diazo compounds and azo coupling components whichwill couple to produce a desired shade. It is necessary that the choiceof the light-sensitive diazo compound and the coupling component be suchas toproduce a dye image possessing the most desirable characteristicsof shade, density, fastnessto lightand to water. Many investigations inthis art have been concerned with the discovery of proper lightsensitivediazo compounds which will have the necessary properties of decomposingon exposure to light, particularly light which emits rays in the 3600 A.to 4200 A. line and, in the undecomposed form, will combine with the azocoupling component to produce the desired image. When the diazo compoundand the azo component are both contained in the light sensitive layer ina two component dry development system, it is further necessary that thediazo compound and the azo component be of such coupling capacity withrespect to each other that they will not prematurely couple prior toexposure and development. The results of these investigations havegenerally prov-en that diazos derived from p-diamines of the benzeneseries are most suitable for the requirements of two-componentdiazotypes.

In the reproduction of drawings, printed material, pictures, or otheroriginals to b copied, it is often of particular advantage to make anintermediate print or transition print on a transparent diazotypecopying material by exposing a transparent sensitized diazotype materialto actinic rays, such as ultraviolet light, by either the printingthrough or reflex process and then developing the diazotype exposure.The development of the diazotype material can be. carried outhyany Qf :2th methods k own to the ar io the ev l Qi ex osed di ty s- T u whe e atw eomponen s st m h b en e pl yed, w ch contains the azocomponent inthe light-sensitive layer in combination with the diazo compound,development may be effected by passing the expesed diazotype through anatmosphere of ammonia vapgrs. Where a one-component system has beenemployed, which contains the diazo compound as th only dye component inthe lightsensitive layer, the image is developedby treating the eggposeddiazotype with an alkaline solution containing the azo component by adipping or fog spraying method. In either case, the image produced onthe transparent intern'iediate or transition diaz otype print can beused for the reproductionoi'iurther diazotype prints or, if desiredforthereproduction oftheimage onany photoprinting material capable offurther reproducing the ima e Thi me'thed eih o ing n m dia o t e sitiondiazotype prints is particularly useful when it'is desired to makealarge number of reproductiqns from a frail or valuable original whicheould not stand the wear of repeated exposures which would be necessaryto make the desired number of copies. The eiiiciencyof this process forthe production of further photo copies from-a transition or intermediatediazotype print depends upon the opacity of the azo dyeimage toultraviolet light, and upon the transparency of the background to suchlight. It also depends upon the visual density of the image produced onthe transition print. Images of; poor'visuai density, such as lightyellows on a white-background, although they, may have the desireddegree of opacity to ultraviolet light, nevertheless have thedisadvantage-of renderingdifiicult the detection of flaws in theintermediate image.

good visual density have been obtained from diazotypes using azocomponents known to the artfor general diazotype work, such asphloroglucinol, 2,3-dihydroxynaphthalen and ,c-naphtho1-3,6-disulfonicacid. However, despite the good visual density of 'the'colors obtainedand, in some cases, the satisfactory fastness to light and to water ofthe image, they do not have the light opacity or photographic densitynecessary to reproduce the image satisfactorily in subsequent copies.The azo dye componentused for the production of transition print imagesmust be such as to produce, oncoupling with the diazo compound employed,a color which will sufliciently absorb the ultraviolet light incidentupon it during exposure to prevent light decomposition of the diazocompound in the areas to be reproduced from, the, transition op est is.th r f r a further object of h n en ion to pr c a ht-sens tive ma erialw ch ll r p o uce th Diazotype prints of a deep or dark color having 7image of the original in a shade having improved photographic density oropacity to ultraviolet light.

.Azo components, such as resorcinol, have heretofore been employed inthe production of diazotype prints and others have been suggested inorder to obtain color images having the'necessary light absorptioncharacteristics for transition printing. Resorcinol will reproduce theimage on the transition print in a sepia or orangebrown color which hasgood visual density and good opacity to ultraviolet light. However, theprints obtained from these components are often lacking in theproperties of fastness to light and to water, and their couplingcapacities are such that they do not have the proper resistance topremature coupling for use in two-component systems. The dye imagesproduced on transparent intermediate prints, particularly when thesupport used for the print is a plastic unsupported film or a plasticcoated base, have a tendency to diffuse, thereby reducing the contrastof the image and producing blurred effects on the final reproduced copy.

Some components have been studied which will not migrate in the plasticlayer and produce dye images which will have no tendency to migrate orofi-set. Such components have, however, produced colors of low visualdensity. It is, therefore, the object of this invention to produce adiazotype composition on a plastic surfaced layer which will combinegood visual density with nonmigratory properties, good opacity toactinic light and good resistance to precoupling.

With this object in view it has now been found that 3,3, 5,5'-tetrahydroxy biphenyl can be successfully employed as the coupling componentin a two component diazotype light sensitive layer on a plastic surface.When so used it does not prematurely couple with the diazo compound nordoes it migrate or diifuse in the plastic layer and upon exposure anddevelopment by coupling in the usual way with p-phenylene diamine diazocompounds produces images of high visual density and high opacity toultra-violet or other actinic light. The images produced from the 3,3,5,5'-tetra hydroxy biphenyl will not difiuse into the plastic layer ofthe carrier and will remain sharp and have no tendency to bleed oroff-set under pressure onto other plastic surfaces which may be incontact with the surface carrying the reproduced image. These imageswill also have good fastness to light and to water.

Having this unique combination of properties, the 3,3, 5,5-tetra hydroxybiphenyl coupling component is particularly suited for use in twocomponent diazotype coatings for plastic surfaced carriers which may beemployed in transition diazotype printing.

The azo coupling component 3,3, 5,5'-tetrahydroxy biphenyl or5,5'biresorcinol has the structural formula It may be prepared by firstdeaminating 3,3'-

dipotassiumsulfonate according to the schematic reaction- A 0 H 0 3H IIg 0 3K g 0 K 3,3, 5,5-diphenyltetrapotassiumsulfonate is then preparedfrom product II by heating 5 pts. of the latter with 3.45 pts. sulfuricacid monohydrate and 7.85 pts. 65% oleum for 15 hours at 220 C.; thereaction product is diluted with water, S04 ion removed as BaSO4,filtered, the

, filtrate neutralized with KOH and the potassium salt isolated. 50 pts.of the latter are then fused with 425 pts. KOI-I for 3 hours at 310 C.;the fusion mixture diluted with water, acidified with H01 and the finalproduct isolated by extraction, the schematic reaction being as follows:

In the preparation of the diazotype photoprinting materials of thisinvention, a base material or carrier such as plastic coated paper iscoated by means known to the art, as for instance by the bead-dipmethod, with a coating solution containing the 3,3, 5,5'-tetra hydroxybyphenyl and a suitable diazo compound. The plastic material comprisingthe coating on the carrier may be cellulose acetate, cellulose butyrateand other cellulose esters, cellulose ethers, and polyvinyl plastics.The carrier may be composed entirely of one of these plastic materials.

In addition to the dye components the coating solution may contain uchother materials as are ordinarily used in the preparation of diaaotypetwo-component light sensitive coating. These include stabilizingmaterials for the coating composition, such as citric acid, phosphoricacid and thiourea; swelling agents for cellulose acetate or otherplastic material, such as isopropanol, gamma valerolactone, ethylalcohol, methyl alcohol, butanol, ethyl lactate acetone, diacetonealcohol, ethyl methyl ketone and methyl glycol; and other adjuvants andaddition agent designed to improve the resistance of the diazotypesolution and coating to premature coupling and to prevent aging of thedecomposition products and consequent discoloration in the background.

As diazo compounds, any suitable light sensitive diazo compound whichwill couple with the 3,3, 5,5-tetrahydroxy biphenyl and which has theother properties necessary for use in twocomponent diazotype compositionmay be employed. It is preferred, however, to use diazo compoundsderived from p-diamines of the henzene series. Diazo compounds of otherclassifications, such as diazoanhydrides of o-amino hydroxy naphthalenecompounds have been found suitable for diazotype two-componentcompositions. However, the diazo compounds of the pdiamine of thebenzene series are preferred and of these those which are most suitablecarry N- substituents on the undiazotized amino group; the substituentgroups being alkyl, alkoxy, aryl, aralkyl, alkylol, alicyclic, aromaticand heterocyclic groups. Examples of these preferred diazo compounds areas follows:

These diazo compounds may be used in the form of their stabilized salts,such as the ZnClz, CdClz, or SnCh double salts; the fluoroborates, thearyl or alkyl sulfonates; or the acid sulfates of the diazoniumchloride.

The following specific example will serve to illustrate further theinvention, it being under stood, however, that it is not intended tolimit its scope. Unless otherwise stated, the parts are by weight.

Example A coating solution is prepared by mixing the followingmaterials:

50 cc. water 40 cc. isopropanol 2 gs. citric acid 1 gr. zinc chloride 2gs. thiourea cc. 'y valeralactone 5 gs. sulfosalicylic acid 5 gs. formicacid 4.5 gs. zinc chloride double alt of p-diethylamino benzenediazoniumchloride 3 gs. 5,5 tetra hydroxy biphenyl After mixing, this coatingsolution is filtered through a bed of activated charcoal and is thencoated on to a cellulose acetate coated paper base by means of thebead-dip coating method. The coated plastic surfaced paper is then driedin the usual manner by drawing it through a heated drying chamber. Uponsubmitting the thus processed paper to accelerated aging tests andprolonged storage tests under average conditions of temperature andhumidity it is found that the diazotype coating on the plastic surfacedbase has a' high degree of resistance to precoupling or spontaneouscoupling while in storage.

Upon exposing the coated and dried plastic Slll faced paper to actiniclight such as light rich in ultraviolet emissions under an originalpattern to be reproduced and developing by drawing the exposed ensitizedpaper through an atmosphere of ammonia vapors, the original isreproduced in a deep reddish brown color of excellent contrast against aclear background. This image has excellent light fastness and waterfastness properties and is highly absorptive of ultraviolet radiation.The prints containing the reproduced image are, therefore, especiallyvaluable a intermediate or transition prints in the production offurther diazotype or other light sensitive copies.

In the above example such diazo compounds asp-diazo-N-methylN-hydroxyethylaniline, ZnClz double salt andN-benzyl-N-ethylaniline, p-diazoniumchloride SnClr double salt may besubstituted for the p-diethylamino benzenediazonium chloride ZI1C12double salt therein used with equivalent results and as indicated"above, any other suitable light ensitive diazo compound for theproduction of'a particular color effect may be likewise substituted.

Having now particularly described my invention and illustrated the bestmanner in which to perform it, what I claim as new and desire to protectby Letters Patent is:

1. A diazotype photoprinting material com-' prising a plastic surfacedcarrier and superimposed on the plastic surface thereof a coatingcontaining 3,3, 5,5'-tetra hydroxy biphenyl and a light sensitive diazocompound.

2. A diazotype photoprinting material comprising a plastic surfacedcarrier and superimposed on the plastic surface thereof a coatingcontaining 3,3, 5,5'-tetra hydroxy biphenyl and alight sensitivep-aminobenzene diazo compound.

3. A diazotype photoprinting material comprising a plastic surfacedcarrier and superimposed on the plastic surface thereof a coatingcontaining 3,3, 5,5'-tetra hydroxy biphenyl and a light sensitivep-diazo-N-alkyl aniline compound.

4. A diazotype photoprinting material comprising a plastic surfacedcarrier and superimposed on the plastic surface thereof a coatingcontaining 3,3, 5,5-tetra hydroxy biphenyl and p-diazo-N-diethylaniline.

FRED W. N EUMANN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS ame Date

1. A DIAZOTYPE PHOTOPRINTING MATERIAL COMPRISING A PLASTIC SURFACEDCARRIER AND SUPERIMPOSED ON THE PLASTIC SURFACE THEREOF A COATINGCONTAINING 3,3'', 5,5''-TETRA HYDROXY BIPHENYL AND A LIGHT SENSITIVEDIAZO COMPOUND.